[IMP] payment: add Boleto icon

Prior to this commit, the icon for the Boleto payment method was
missing.
This commit adds this missing icon.

task-3557094

closes odoo/odoo#138899

Signed-off-by: Antoine Vandevenne (anv) <anv@odoo.com>

addons/payment/data/payment_method_data.xml

@@ -3630,7 +3630,7 @@
         <field name="code">boleto</field>
         <field name="sequence">1000</field>
         <field name="active">False</field>
-        <field name="image" type="base64" file="payment/static/img/cash_app_pay.png"/>
+        <field name="image" type="base64" file="payment/static/img/boleto.png"/>
         <field name="support_tokenization">False</field>
         <field name="support_express_checkout">False</field>
         <field name="support_refund"></field>